Why I Two-Space

Posted on October 12th, 2012.

If you look at the source code for this blog, you might notice that all my blog posts (written in Markdown) have two spaces after every period.

Every so often this Slate article makes the rounds and annoys me. This time I figured I'd write a blog post/rant to get it off my chest once and for all: two-spacing is equal or superior to one-spacing in all non-trivial ways.

  1. The Arguments for One-Spacing
  2. Effort
  3. Two-Spacing is Ugly
    1. Source and Presentation
    2. Typewriters
  4. Power
  5. Final Score

The Arguments for One-Spacing

If you read the aforementioned Slate article you'll see that it presents a total of three arguments in favor of single-spacing after a period:

  1. Many professional typographers find two-spacing ugly (though they have no actual evidence of its effects on readability).
  2. It's less work to press the space bar once instead of twice.
  3. It's pretty much arbitrary anyway, so why not?

You might also infer from the article's tone that "you get to feel superior to those Neanderthals that use two spaces" is another argument in favor of it, but I'll leave that one out because it can go both ways.

Let's go through these arguments one by one and see how they hold up.


I don't think the "it's more effort to press the space bar twice" argument is at all compelling. The extra space may account for around half a percent of the keystrokes you type, depending on how long your sentences tend to run (mine usually end up fairly long, as you can see).

Not only is it not a large portion of your keystrokes, but the space bar has your two strongest digits dedicated solely to it! If any fingers are going to wear out from typing, it won't be your thumbs.

You could get pedantic and mention increased file size as a disadvantage of two spacing, but let's not quibble about a few bytes when I can hold 32 gigabytes on an SD card the size of a postage stamp.

Two-Spacing is Ugly

The Slate article is correct is saying that many professional typographers think two-spacing is ugly. My copy of The Elements of Typographic Style agrees. However, there's more to the issue than a single blanket rule.

Source and Presentation

If you're reading this in a web browser and look closely, you'll notice that there's only one space between each sentence. I said I used two, so what happened?

Web browsers, by default, collapse successive whitespace into a single space when it renders the HTML. You could put a thousand spaces between sentences in the source and it would still come out single-spaced.

Another widely-used format, LaTeX, splits the difference and actually uses somewhere between one and two spaces (by default).

The key idea here is that what you type and what the end user actually reads are two different things. They don't need to be bound together. It's possible to type two spaces but get one in your output (or in LaTeX's case: an even more pleasing "one and a bit").

If you're using a WYSIWYG editor like Microsoft Word this may not be the case. For the high school students typing up papers for class: sure, go ahead and single-space. But if you're still using Word to type up things like books, long blog posts, or technical documentation, you're doing yourself a disservice. Learn to use a system like LaTeX so your source and rendered output aren't locked together.

This means that "two-spacing looks ugly" doesn't imply "you should not type two spaces when you write". It actually implies "you should use a system that results in single-spacing when rendered", and most of the common ones today will do exactly that.


So we've seen that the "extra spaces take more effort" argument isn't convincing, and that "two-spacing in the final output is ugly" doesn't prevent you from using two spaces in the input.

But so far I haven't given you any reason for using two spaces. That's the Slate article's third argument: "it's arbitrary anyway, so you may as well use one".

Let's fix that by examining the common holier-than-thou put-down of "two-spacing was useful back when people used typewriters, you dinosaur!".

To his credit, the Slate author correctly points out that it's not the fact that people used typewriters that made two-spacing popular, it was the fact that typewriters used monospaced fonts. Most people miss that logical leap.

Unfortunately he follows that up with:

Here's the thing, though: Monospaced fonts went out in the 1970s.

For the average person typing up a school paper here and there, sure. But for many people doing a large amount of writing for LaTeX books and papers, technical documentation, code comments, mailing lists, blog posts, and lots of other things, it's simply wrong for one big reason:

Text editors use monospaced fonts!

It doesn't matter what editor you use. Vim, Emacs, TextMate, Sublime Text, Eclipse, Gedit, Notepad++? All of them use monospaced fonts.

Going back to the typewriter quip, this means that if people used two spaces when writing on typewriters because it looked better, then using two spaces in a text editor will look better. And we know that because there's a distinction between source and presentation in non-WYSIWYG contexts, we can use separate strategies for each.

We can have our cake and eat it too! We can type two spaces after a period to make our text look better as we write, revise, and edit it, and then render it to single-spacing (or "space-and-a-half-ing") to give our readers a beautiful reading experience with pleasant spacing.

So now two-spacing has a real advantage over single-spacing. That's enough to make it preferable. But let's look at one more advantage for power users, just to seal the deal.


If you use Vim to edit text, you're probably familiar with its "text objects". Text objects are what let you move and act on whole chunks of text at a time. For example, instead of deleting a word letter-by-letter you can use daw to "delete around word".

Vim comes with a "sentence" text object built-in. You can move around your document sentence-by-sentence with ( and ), and yank/delete/change/etc entire sentences with cas ("change around sentence") and so on.

You can probably guess where this is going. If you single-space sentences Vim will do its best to "do the right thing", but inevitably gets tripped up when you've got punctuation in your sentence. For example:

Bob started speaking. Hello, Mr. Smith! How are you today?

What happens when you tell Vim to "delete around sentence" now?

Bob started speaking. Hello, Mr. How are you today?

Well that's not right! Vim can't easily tell the difference between the period after "Mr" and the end of a sentence. What happens if you type your prose with two-spacing instead?

Bob started speaking.  Hello, Mr. Smith!  How are you today?
Bob started speaking.  How are you today?

This time Vim is able to delete the sentence correctly! Note that you'll need to make sure to set cpo+=J in your ~/.vimrc file to tell Vim "don't worry, I'm using two spaces like a sane person" for this to work.

Two-spacing provides more semantic information, which means that software can parse and work with it more easily. I'm sure Emacs has something similar, and if you or someone else ever needs to parse your writing programatically they'll have an easier time.

Final Score

To recap, the arguments for single-spacing are:

  1. Two-spacing is ugly in proportional fonts.
  2. It's less work to press the space bar once instead of twice.
  3. It's pretty much arbitrary anyway, so why bother with two?

Number 1 is irrelevant, because writing and rendering are (except in trivial cases) two orthogonal activities.

Number 2 isn't very convincing.

Number 3 is false, because two-spacing gives you two advantages over one-spacing:

  1. It looks better in your editor.
  2. It gives you more power when editing and parsing.

So the next time you see that arrogant Slate article, feel free to be arrogant right back. Wield your extra spaces proudly, because they give you both comfort and power!